This invention relates in general to earth boring bits, and in particular to a bearing seal for earth boring bits.
This invention concerns particularly the type of earth boring bit that employs three rotatable cutters mounted on depending bearing shafts. Each conical cutter rotates on its bearing shaft as the drill bit is rotated. The cutter has teeth of tungsten carbide inserts on its exterior for disintegrating the earth. The bearings are usually either a journal type, or they may employ roller bearings. The bearings are supplied with lubricant and sealed by an elastomeric seal located in a groove formed in the bearing shaft at its base.
Because of tolerances, particularly with the roller bearing type bearings, the cutter will have radial, axial and angular movements relative to the bearing shaft. The seal, which usually is in sliding contact with the cutter, will experience varying degrees of pressure because of this movement, tending to cause leakage. There have been several proposals in the past to provide a floating seal that is able to move radially to accommodate the cutter movement.